Determine the effects of the following on a cash basis taxpayer's gross income for 2015 and 2016.
a. On the morning of December 31, 2015, the taxpayer received a $1,500 check from a customer. The taxpayer did not cash the check until January 3, 2016.
b. The same as part (a), except the customer asked the taxpayer not to cash the check until January 3, 2016, after the customer's salary check could be deposited.
c. The same as part (a), except the check was not received until after the bank had closed on December 31, 2015.